Web browsers are conventionally used to display documents created with a standard descriptive language such as Hyper Text Markup Language (HTML). Documents written in such languages can be displayed with various visual and audio effects such as color, animation, sound effects, and the like. The documents may include text, bitmap images, graphics, and other types of content.
Web browsers (or, more generally, “document browsers”) typically provide functions which permit a user to advance forward and backward among a series of related pages; to jump to a specified page; to jump to pages that are referenced via a so-called “hyperlink” embedded in a page; and to maintain a list of recently viewed pages. Although frequently used to navigate through web pages on the Internet, document browsers can be used to display pages that reside on a local area network or even a local computer on which the browser executes.
Recently, as computers have become smaller, it has become possible to run browsers on notebook computers, palm-sized computers, and so-called “tablet and stylus” computers. The latter devices typically comprise a thin computer roughly the size of a sheet of paper with a large writing surface that doubles as a display, and a stylus that substitutes for a keyboard. A user can display and edit documents using the stylus as a writing instrument.
One potential application for such hand-held computers is the display of mass-produced documents such as books, maps, and other descriptive material. For example, a user who purchases a textbook or fictional work on a CD-ROM or other medium can display the work using a small computer such as a tablet-based computer.
In some instances, a user may want to annotate or otherwise mark pages displayed on the computer. Using a conventional word processing program, a user can rearrange text, highlight certain words or phrases, or delete portions of the text. Such features require that the user have access to the underlying content (e.g., the descriptive material that forms the work). In the case of copyrighted materials, however, editing capabilities may not be available to modify the underlying materials. Certain text may be copy-protected or otherwise unavailable for editing using normal editing tools, or may not be in a format suitable for word processing. In such circumstances, there may be no practical way for a user to annotate such works. As one example, a student viewing a copy-or edit-protected textbook on a tablet-based computer may have no practical way of making notes directly in the textbook. Such a feature would be desirable notwithstanding the copy protection or unavailability of general editing functions for the document.